AP_OpticalFlow: fixed example build
AP_Mission: Change jump_to_landing_sequence to get_landing_sequence_start
Plane: Bugfix.  Changing to landing sequence now works at mission end.
Plane: minor code style change

use comment and function style consistent with rest of code
Plane: move set_mode() after mission.set_current_cmd()

if set_current_cmd() fails, we don't want to change to AUTO with some
unknown mission item
Plane: "Go around" operation. Assumes go around behavior follows land wp.
Plane: save a byte in auto_state

keep single bits together to save space on APM2
Plane: removed impossible boolean check
Plane: reset commanded_go_around at start of land

this allows multiple landing attempts
Plane: fixed verify_land() comment for go-around
Plane: removed incomplete DF log of go-around

the right commands should already be logged. This code would have
logged a lot of uninitialised bytes
Plane: increase mav throttle slew rate in generated param docs
Replay: cope with old copter attitude and baro msgs
AP_AHRS: cope with 90 degree pitch in update_trig()

this prevents a numerical error in Replay
Copter: fix to dcm-check to be continuous

dcm-check was triggering after 10 bad headings but these did not need to
be continuous meaning if the vehicle was flown long enough it would
almost certainly trigger a dcm-check failure and land
LogAnalyzer: balance/twist initial commit
LogAnalyzer: updated testCompass to match our prearm check
LogAnalyser: TestBalanceTwist sanity check of motor values
LogAnalyser: rename BalanceTwist to MotorBalance
AC_AttControl: add sqrt_controller

Original code by Jonathan Challinger